Multimodal dielectric resonance device, dielectric filter, composite dielectric filter, synthesizer, distributor, and communication apparatus

ABSTRACT

A multimode dielectric resonator device is provided in which a dielectric core can be easily disposed in a cavity, a dielectric resonator device comprising resonators in plural stages can be obtained, and the Q 0  is maintained at a high value. Dielectric cores  1   b,    1   c  to resonate in plural modes such as TM 01  δ−(x−z), TE 01 δ−y, TM 01 δ−(x+z) or the like are supported substantially in the center of a cavity  2  by means of a support  3,  in the state that the cores are substantially separated from the inner walls of the cavity  2  at a predetermined interval, respectively.

TECHNICAL FIELD

The present invention relate to an electronic component, and moreparticularly to a dielectric resonator device, a dielectric filter, acomposite dielectric filter, a synthesizer, a distributor, and acommunication device including the same, each of which operates in amultimode.

BACKGROUND ART

A dielectric resonator in which an electromagnetic wave in a dielectricis repeatedly totally-reflected from the boundary between the dielectricand air to be returned to its original position in phase, wherebyresonance occurs is used as a resonator small in size, having a highunloaded Q (Q₀). As the mode of the dielectric resonator, a TE mode anda TM mode are known, which are obtained when a dielectric rod with acircular or rectangular cross section is cut to a length of s·λg/2 (λgrepresents a guide wavelength, and s is an integer) of the TE mode orthe TM mode propagating in the dielectric rod. When the mode of thecross section is a TM01 mode and the above-described s=1, a TM01δ moderesonator is obtained. When the mode of the cross section is a TE01 modeand s=1, a TE01δ mode dielectric resonator is obtained.

In these dielectric resonators, a columnar TM01δ mode dielectric core ora TE01δ mode dielectric core are arranged in a circular waveguide orrectangular waveguide as a cavity which interrupts the resonancefrequency of the dielectric resonator, as shown in FIG. 27.

FIG. 28 illustrates the electromagnetic field distributions of theabove-described two modes in the dielectric resonators. Hereupon, acontinuous line represents an electric field, and a broken line amagnetic field, respectively.

In the case where a dielectric resonator device having plural stages isformed of dielectric resonators including such dielectric cores, theplural dielectric cores are arranged in a cavity. In the example shownin FIG. 27, the TM01δ mode dielectric cores shown in (A) are arranged inthe axial direction, or the TE01δ mode dielectric cores shown in (B) arearranged along the same planed

However, in such a conventional dielectric resonator device, to provideresonators in multi-stages, it is needed to position and fix pluraldielectric cores at a high precision. Accordingly, there has been theproblem that it is difficult to obtain dielectric resonator deviceshaving characteristics with no variations.

Further, conventionally, TM mode dielectric resonators each having acolumnar or cross-shaped dielectric core integrally provided in a cavityhave been used. In a dielectric resonator device of this type, the TMmodes can be multiplexed in a definite space, and therefore, aminiature, multistage dielectric resonator device can be obtained.However, the concentration of an electromagnetic field energy onto themagnetic cores is low, and a real current flows through a conductor filmformed on the cavity. Accordingly, there have been the problem thatgenerally, a high Qo comparable to that of the TE mode dielectricresonator can not be attained.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a multi-modedielectric resonator device in which dielectric cores can be easilyarranged in a cavity, a dielectric resonator device comprisingresonators in plural stages can be obtained, and the Q₀ is maintained ata high value.

Moreover, it is another object of the present invention to provide adielectric filter, a composite dielectric filter, a synthesizer, adistributor, and a communication device, each including theabove-described multimode dielectric resonator.

In the multimode dielectric resonator device of the present invention,as defined in claim 1, a dielectric core having a substantialparallelepiped-shape, operative to resonate in plural modes is supportedsubstantially in the center of a cavity having a substantialparallelepiped-shape in the state that the dielectric core is separatedfrom the inner walls of the cavity at predetermined intervals,respectively. Since the substantial parallelepiped-shape dielectric coreis supported substantially in the center of the cavity having asubstantial parallelepiped-shape, as described above, the supportingstructure for the dielectric core is simplified. Moreover, since thedielectric core having a substantial parallelepiped-shape, operative toresonate in plural modes is employed, plural resonators can be formedwithout plural dielectric cores being arranged. A dielectric resonatordevice having stable characteristics can be formed.

For supporting the dielectric core in the cavity, a support having alower dielectric constant than the dielectric core is used, as definedin claim 2. Thereby, the concentration of an electromagnetic fieldenergy to the dielectric core is enhanced, and the Q₀ can be maintainedat a high value.

A supporting portion for the dielectric-core in the cavity may be moldedintegrally with the dielectric core or cavity, as defined in claim 3.Thereby, the support as an individual part becomes unnecessary. Thepositional accuracy of the supporting portion with respect the cavity ordielectric core, and moreover, the positioning accuracy of thedielectric core in the cavity are enhanced. Accordingly, a multimodedielectric resonator device having stable characteristics can beinexpensively obtained.

The supporting portion or support, as defined in claim 4, is provided ina ridge portion of the dielectric core or in a portion along a ridgeline of the dielectric core, or is provided near to an apex of thedielectric core, as defined in claim 5. Thereby, the mechanical strengthof the supporting portion per the overall cross sectional area thereofcan be enhanced. Further, in the TM modes, the reduction of the Q₀ ofthe mode where the supporting portion or support is elongated in thevertical direction to the rotation plane of a magnetic field can beinhibited.

The supporting portion or support, as defined in claim 6, is provided inthe center of one face of the dielectric core. Thereby, the reduction ofthe Q₀ of a mode different from the TM mode where the supporting portionor support is elongated in the vertical direction to the rotation planeof the magnetic field can be inhibited.

As defined in claim 7, a part of or the whole of the cavity is anangular pipe-shape molded-product, and the dielectric core is supportedto the inner walls of the molded product by means of the support orsupporting portion. According to this structure, by setting themold-drafting direction to be coincident with the axial direction of theangular pipe-shape, the cavity and the dielectric core can be easilymolded by means of a mold having a simple structure.

Also, according to this invention, formed is a dielectric filter byproviding an externally coupling means to couple to a predetermined modeof the multimode dielectric resonator device.

Further, according to this invention, formed is a composite dielectricfilter having at least three ports by use of plural above-describeddielectric filters.

Further, according to this invention, formed is a synthesizer comprisingindependently, externally coupling means to couple to pluralpredetermined modes of the multimode dielectric resonator device,externally, independently, and a commonly externally coupling means tocouple to plural predetermined modes of the multimode dielectricresonator device externally commonly, wherein the commonly externallycoupling means is an output port, and the plural independentlyexternally coupling means are input ports.

Further, according to this invention, formed is a distributor comprisingindependently, externally coupling means to couple to predeterminedmodes of the multimode dielectric resonator device, respectively,independently, and a commonly externally coupling means to couple toplural predetermined modes of the multimode dielectric resonator devicecommonly, externally, wherein the commonly externally coupling means isan input port, and the plural independently externally coupling meansare output ports.

Moreover, according to the present invention, a communication device isformed of the composite dielectric filter, the synthesizer, or thedistributor each described above, provided in the high frequency sectionthereof.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing the constitution of the basicportion of a multimode dielectric resonator device according to a firstembodiment.

FIG. 2 consists of cross sections showing the electromagnetic fielddistributions in the respective modes of the above resonator device.

FIG. 3 consists of cross sections showing the electromagnetic fielddistributions in the respective modes of the above resonator device.

FIG. 4 consists of cross sections showing the, electromagnetic fielddistributions in the respective modes of the above resonator device.

FIG. 5 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the intervalsbetween the supports are changed.

FIG. 6 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the intervalsbetween the supports are changed.

FIG. 7 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the intervalsbetween the supports are changed.

FIG. 8 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the intervalsbetween the supports are changed.

FIG. 9 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the intervalsbetween the supports are changed.

FIG. 10 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the intervals ofsupports are changed.

FIG. 11 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the thicknesses ofthe supports are changed.

FIG. 12 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the thicknesses ofthe supports are changed.

FIG. 13 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the thicknesses ofthe supports are changed.

FIG. 14 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the thicknesses ofthe supports are changed.

FIG. 15 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the thicknesses ofthe supports are changed.

FIG. 16 illustrates the changes of the characteristics in the respectivemodes of the above resonator device, occurring when the thicknesses ofthe supports are changed.

FIG. 17 is a perspective view showing the constitution of the basicportion of a multimode dielectric resonator device according to a secondembodiment.

FIG. 18 is a graph showing the changes of the resonance frequencies inthe respective modes of the above resonator device, occurring when thesizes of respective portions of the device are changed.

FIG. 19 is a graph showing the changes of the resonance frequencies inthe respective modes of the above resonator device, occurring when therespective portions of the device are changed.

FIG. 20 is a graph showing the changes of the resonance frequencies inthe respective modes of the above resonator device, occurring when thesizes of respective portions of the device are changed, respectively.

FIG. 21 shows a process of manufacturing the above resonator device.

FIG. 22 consists of perspective views each showing the constitution ofthe basic portion of a multimode dielectric resonator device accordingto a third embodiment.

FIG. 23 is a perspective view showing the constitution of the basicportion of a multimode dielectric resonator device according to a fourthembodiment.

FIG. 24 is a graph showing the changes of the resonance frequencies inthe respective modes of the above resonator device, occurring when thesizes of respective portions of the device are changed.

FIG. 25 is a perspective view showing the configuration of the basicportion of a multimode dielectric resonator device according to a fifthembodiment.

FIG. 26 is a perspective view showing the configuration of the basicportion of a multimode dielectric resonator device according to a sixthembodiment.

FIG. 27 consists of partially exploded perspective views each showing anexample of the configuration of a conventional dielectric resonatordevice.

FIG. 28 illustrates the electromagnetic field distributions as anexample of a conventional single mode dielectric resonator.

FIG. 29 is a perspective view showing the configuration of the basicportion of a multimode dielectric resonator device according to aseventh embodiment.

FIG. 30 consists of cross sections each showing the electromagneticfield distributions in the respective modes of the above resonatordevice.

FIG. 31 consists of cross sections showing the electromagnetic fielddistributions in the respective modes of the above resonator device,respectively.

FIG. 32 consists of cross sections showing the electromagnetic fielddistributions in the respective modes of the above resonator device,respectively.

FIG. 33 consists of graphs showing the relations between the thicknessof the dielectrics core of the above resonator device and the resonancefrequencies in the respective modes.

FIG. 34 illustrates the configuration of a dielectric filter.

FIG. 35 illustrates the configuration of another dielectric filter.

FIG. 36 illustrates the configuration of a transmission receptionshearing device.

FIG. 37 illustrates the configuration of a communication device.

BEST MODE FOR CARRYING OUT THE INVENTION

The configuration of a multimode dielectric resonator device accordingto a first embodiment Will be described with reference to FIGS. 1 to 16.

FIG. 1 is a perspective view showing the basic constitution portion ofthe multimode dielectric resonator device. In this figure, referencenumerals 1, 2, and 3 designate a substantially parallelepiped-shapeddielectric core, an angular pipe-shaped cavity, and supports forsupporting the dielectric core 1 substantially in the center of thecavity 2, respectively. A conductor film is formed on the outerperipheral surface of the cavity 2. On the two open-faces, dielectricplates or metal plates each having a conductor film are disposed,respectively, so that a substantially parallelepiped-shaped shield spaceis formed. In addition, an open-face of the cavity 2 is opposed to anopen-face of another cavity so that electromagnetic fields inpredetermined resonance modes are coupled to provide a multistage.

The supports 3 shown in FIG. 1, made of a ceramic material having alower dielectric constant than the dielectric core 1 are disposedbetween the dielectric core 1 and the inner walls of the cavity 2 andfired to be integrated. The dielectric core may be disposed in ametallic case, not using such a ceramic cavity as shown in FIG. 1.

The resonance modes, caused by the dielectric core 1 shown in FIG. 1,are illustrated in FIGS. 2 to 4. In these figures, x, y, and z representthe co-ordinate axes in the three-dimensional directions as shown inFIG. 1. FIGS. 2 to 4 show the cross-sections of the respectivetwo-dimensional planes, respectively. In FIGS. 2 to 4, a continuous linearrow indicates an electric field vector, and a broken line arrowindicates a magnetic field vector. Symbols “•” and “×” represent thedirection of an electric field and that of a magnetic field,respectively. FIG. 2 to 4 show only a total of six resonance modes,namely, the TM01δ modes in the three directions, that is, x, y, and zdirections, and the TE01δ modes in the three directions. In practice,higher resonance modes exist. In ordinary cases, these fundamental modesare used.

The characteristics of the multimode dielectric resonator device shownin FIGS. 1 to 4 are changed depending on the relative positionalrelations between the supports 3 and the dielectric core 1 or the cavity2, and the properties of materials, which are illustrated in FIGS. 5 to16 as an example.

FIGS. 5 to 10 show the change of the resonance frequency and that of theunload Q (hereinafter, referred to as Q₀), occurring when the intervalsCO between the supports 3 are changed while the relative dielectricconstant ε r and the tangent δ of the supports 3 are used as parameters.FIG. 5 shows the TE01δ−z, FIG. 6 the TE01δ−x, FIG. 7 the TE01δ−y, FIG. 8the TM01δ−z, FIG. 9 the TM01δ−x and FIG. 10 the TM01δ−y, respectively.FIGS. 11 to 16 show the change of the resonance frequency and that ofQ₀, occurring when the thickness C1 of the supports 3 is changed. FIG.11 shows the TE01δ−z, FIG. 12 the TE01δ−x, FIG. 13 the TE01δ−y, FIG. 14the TM01δ−z, FIG. 15 the TM01δ−x, and FIG. 16 the TM01δ−y, respectively.In these figures, in (A) shown are the cross sections in the respectivemodes, viewed in the electromagnetic wave propagation direction. Each ofthe dielectric cores 1, shown in these figures, is substantially a cube(regular hexahedron) with one side of 25.5 mm long. The relativedielectric constant ε r is 37, and tan δ is {fraction (1/20,000)}. Thesize of each inner wall of the cavity 2 is 31×31×31 mm, and the wallthickness is 2.0 mm. Accordingly, the size of each of the outer walls is35×35×35 mm. A conductor film is formed on the outer wall surfaces.Accordingly, the cavity space defined by the conductor film has a sizeof 35×35×35 mm. Further, in FIGS. 5 to 10, the thickness of each support3 is 4.0 mm.

As seen in the results shown in FIGS. 5 to 7, in the case of the TEmodes, the resonance frequencies are constant, substantiallyirrespective of the intervals CO between the supports 3, and therelative dielectric constant ε r, and a high Q₀ is obtained,substantially irrespective of the ε r and the tan δ. On the other hand,in the TM modes, as shown in FIGS. 8 to 10, as the c r of the supports 3is increased, the resonance frequency is reduced. As the tan δ isdecreased, the Q₀ is reduced. Further, as shown in FIGS. 8 and 9, in theTM01δ−z and TM01δ−x modes where magnetic fields are distributed in aplane parallel to the directions in which the supports 3 are elongated,as the intervals CO between the supports 3 are wider, that is, as thesupports 3 are nearer to the corner portions of the dielectric core 1,the Q₀ is decreased, and the resonance frequency is reduced. On thecontrary, as shown in FIG. 10, in the TM01 δ−y mode where a magneticfiled H is distributed in a plane perpendicular to the directions inwhich the supports 3 are elongated, as the Co intervals become narrower,that is, the supports 3 are nearer to the center portion of thedielectric core 1, the Q₀ is reduced, and the resonance frequency isdecreased.

Further, as seen in the results shown in FIGS. 11 to 13, in the TEmodes, the resonance frequencies are constant, substantiallyirrespective of the thickness C1 of each support 3, the ε r, and the tanδ, and, relatively high Q₀ can be obtained. On the contrary, in the TMmodes, as shown in FIGS. 14 to 16, as the ε r of the supports 3 isincreased, the resonance frequencies are reduced. As the tan δ isdecreased, the Q₀'s are reduced. Further, in any of the TM modes, as thethickness of the supports 3 is increased, the Q₀'s are considerablyreduced, and the resonance frequencies are changed to a relatively highdegree.

As seen in the above-description, in order to maintain the Q₀ at a highvalue in each TM mode, it is effective to thin the supports 3, reducethe relative dielectric constant, increase the tangent δ, and so forth.In addition, the Q₀ can be maintained at a high value by selecting thepositions of the supports 3 in correspondence to a mode to be used. Forexample, when the TM01 δ−y mode is used, it is suggested to set thepositions of the supports near to the corners of the dielectric core.Further, for the purpose of increasing the Q₀ to be as high as possiblein the TM01δ−z or TM01 δ−x mode, not using the TM01 δ−y mode, it Issuggested to position the supports near to the center of the dielectriccore. Moreover, even if the materials and sizes of the dielectric cores1 are the same, it is possible to resonate the respective modes atpredetermined resonance frequencies, by changing the thickness or thepositions of the supports 3, and by changing the materials.

In the above-described embodiment, :means for coupling the respectiveresonance modes of the dielectric core and an external circuit is notillustrated. In the case where a coupling loop is used, an externalcoupling may be produced by arranging the coupling loop in the directionwhere a magnetic field in a mode to be coupled passes the coupling loop.

Next, the configuration of a multimode dielectric resonator deviceaccording to a second embodiment, in which the attachment positions ofsupports are varied, will be described with reference to FIGS. 17 to 21.

FIG. 17 is a perspective view showing the basic constitution portion ofa multimode resonator device. In this figure, reference numerals 1, 2,and 3 designate a substantially parallelepiped-shaped dielectric core,an angular-pipe shaped cavity, and support's for supporting thedielectric core 1 substantially in the center of the cavity 2. Aconductor film is formed on the outer peripheral surface of the cavity2. In this embodiment, two supports 3 are provided on each of the fourinner walls of the cavity. The other configuration is the same as thatin the first embodiment.

FIG. 18 shows the change of the resonance frequency of TM01δ−z and thatof TM01 δ−x and TM01δ−y, occurring when the wall thickness of the cavity2 in the multimode resonator device shown in FIG. 17 is varied from zeroto a, and the cross sectional area of each support 3 is varied. In thissecond embodiment, the directions in which the supports 3 are protrudedwith respect to the dielectric core 1 lie in the x and y axialdirections, not in the z axial direction. Therefore, as the crosssectional area b of the supports 3 is increased, the resonancefrequencies of the TM01 δ−x and TM01 δ−y modes are considerably reducedas compared with the resonance frequency of the TM01 δ−z mode. Hereupon,since the positions where the supports 3 are protruded are equivalentwith respect to the x and y axial directions, the TM01 δ−x mode and theTM01 δ−y mode are changed similarly to each other. Further, when thewall thickness of the cavity 2 is changed, the effects on the TM01 δ−xand TM01 δ−y modes are greater as compared with those on the TM01δ−zmode. Therefore, the change in wall thickness of the cavity causes theresonance frequencies of the TM01 δ−x and TM01 δ−y modes to changeconsiderably. By setting the wall thickness of the cavity or thecross-sectional area of the supports by utilization of theabove-described relation, the resonance frequencies of the TM01 δ−x andTM01δ−y modes and the resonance frequency of the TM01δ−z can berelatively changed. For example, by previously setting the thickness inthe Z axial direction of the dielectric core it to be thick, theresonance frequencies of the three modes can be coincident with eachother.

FIG. 19 shows the changes of the resonance frequencies of the TE01δ−x,TE01δ−y, and TE01δ−z modes, occurring when the thickness in the z axialdirection of the dielectric core 1 and the cross sectional area of thesupports 3, shown in FIG. 17, are varied. As illustrated, with thethickness in the z axial direction of the dielectric core beingincreased, the resonance frequencies of the TE01δ−x and TE01δ−y modesare reduced to a higher degree. Further, as the cross sectional area ofeach support is increased, the resonance frequency of the TE01δ−z modeis reduced more considerably. By designing appropriately the thicknessin the z axial direction of the dielectric core 1 and the crosssectional area of each support 3 by utilization of these relations, theresonance frequencies of the three modes of TE01δ−x, TE01δ−y, andTE01δ−z can be ma de coincident with each other. Thus, by couplingpredetermined resonance modes, the multistage can be realized.

In the above embodiment, means for coupling the respective resonancemodes generated with the dielectric core is not illustrated. In the casewhere the TM modes are coupled to each other, or the TE modes arecoupled to each other, it is suggested to provide a coupling hole at apredetermined position of the dielectric core in such a manner that theresonance frequencies of an even mode and an odd mode, which are thecoupled-modes of the above-described both modes, have a difference.Further, when a TM mode and a TE mode are coupled to each other, it issuggested to couple both of the modes by breaking the balance of theelectric field strengths of the both modes.

FIG. 20 shows the changes of the resonance frequencies of theabove-described three TM modes, occurring when the wall thickness of thecavity 2, the thickness in the z axial direction of the dielectric core1 and the cross sectional area of the supports 3, shown in FIG. 17, arevaried. When only the wall thickness of the cavity is thickened, theresonance frequency of the TM01 δ−x, TM01 δ−y mode is reduced moreconsiderably than that of the TM01δ−z mode. When the thickness in the zaxial direction of the dielectric core is thickened, the resonancefrequency of the TM01δ−z mode is reduced more considerably as comparedwith the resonance frequencies of the TM01δ−z and TM01δ−y modes.Further, when the thicknesses of the supports are thickened, theresonance frequencies of the TM01δ−x and TM01δ−y modes are reduced moreconsiderably, as compared with the resonance frequency of the TM01δ−zmodel. By utilization of these relations, the resonance frequencies ofthe three modes can be made coincident with each other at characteristicpoints, indicated by p1 and p2 in the figure, for example.

FIG. 21 shows an example of a process of producing the multimodedielectric resonator device shown in FIG. 17. First, as shown in (A), adielectric core 1 is molded integrally with a cavity 2 in the state thatthe dielectric core 1 and the cavity 2 are connected by means ofconnecting parts 1′. Hereupon, molds for the molding are opened in theaxial direction of the cavity 2, through the open faces of the angularpipe-shaped cavity 2. Subsequently, as shown in (B) of the same figure,supports 3 are temporarily bonded with a glass glaze in paste state,adjacently to the connecting parts 1′ and in the places corresponding tothe respective corner portions of the dielectric core 1. Further, Agpaste is applied to the outer peripheral surface of the cavity 2.Thereafter, the supports 3 are baked to bond to the dielectric core 1and the inner walls of the cavity 2 (bonded with the glass glaze),simultaneously when an electrode film is baked. Thereafter, theconnecting parts 1′ are scraped off to produce the structure in whichthe dielectric core 1 is mounted in the center of the cavity 2 as shownin (C) of the same figure. In this case, for the dielectric core 1 andthe cavity 2, a dielectric ceramic material of ZrO2-SnO2-TiO2 type withε r=37 and tan δ={fraction (1/20,000)} is used. For the supports 3, alow dielectric constant dielectric ceramic material of: 2MgO—SiO2 typewith ε r=6 and tan δ={fraction (1/2,000)} is used. Both have nearly thesame liner expansion coefficients. No excess stress is applied to thebonding surfaces between the supports and the dielectric core or thecavity, when the dielectric core is heated, and the environmentaltemperature is changed.

FIG. 22 is a perspective view showing the configuration of thefundamental portion of a multimode dielectric resonator device accordingto a third embodiment. In the example shown in FIG. 17, two supports 3are provided on each of the four faces of the dielectric core 1, so thatthe dielectric core is supported in the cavity by a total of eightsupports. On the other hand, regarding the supports, at least threesupports may be provided for each of the four faces of dielectric core1, as shown in FIG. 22 (A). Further, the supports may be continuous in arib-shape as shown in (B) of the same figure. In these cases, for anexternal impact, a stress is dispersed by the supports 3, and thereby,even if the total cross sectional area of the supports 3 is reduced,correspondingly, predetermined mechanical strengths can be maintained.

FIG. 23 is a perspective view showing the configuration of thefundamental portion of a multimode dielectric resonator device accordingto a fourth embodiment. In this figure, reference numeral 3′ designatesa support formed by molding integrally with a dielectric core 1 and acavity 2. Like this, by shaping the support 3′ such that it is differentin the respective axial directions of x, y, and z, especially, theresonance frequencies in the three modes, that is, the TM01 δ−x, TM01δ−y, and TM01δ−z modes can be designed desirably to some degree.

FIG. 24 illustrates the example. As the wall thickness a of the cavityis thickened, the resonance frequencies of the TM01 δ−x and TM01 δ−ymodes are reduced more considerably as compared with the resonancefrequency of the TM01δ−z mode. As the thickness in the z axial directionof the dielectric core is thickened, the resonance frequency of theTM01δ−z mode is more reduced as compared with the resonance frequenciesof the TM01 δ−x and TM01 δ−y modes. Further, as the width of eachsupport 3′ is widened, the resonance frequency of the TM01 δ−x mode isreduced more considerably than that of the TM01 δ−y mode, and theresonance frequency of the TM01 δ−y mode is reduced more considerablythan that of the TM01δ−z. As seen in these relations, the resonancefrequencies in the three modes can be made coincident at acharacteristic point indicated by p1 in the figure. The resonancefrequencies in the two modes can be made coincident with each other atcharacteristic points indicated by p2 or p3.

FIG. 25 is a perspective view showing the configuration of the basicportion of a multimode dielectric resonator device according, to a fifthembodiment. In this figure, reference numeral 3′ designates a supportingportion formed by molding integrally with a dielectric core 1 and acavity 2. In the example shown in FIG. 1, the supports 3 are provided inthe four corners on the upper side and the underside, viewed in thefigure, of the dielectric core 1, respectively. On the other hand, inthe example shown in FIG. 25, some of the supporting portions 3′ areprovided in corner portions of the dielectric core,land the others areprovided in separation from the corner portions. As describedpreviously, the Q₀ and the resonance frequency are changed, depending ofthe relative positional relation between the dielectric core and thesupporting portions. Accordingly, by designing the positions of thesupporting portions 3′ in correspondence to a resonance mode to be used,the resonance frequency in the predetermined mode can be set at apredetermined value without the Q₀being reduced considerably. Bydisposing the respective supporting portions at shifted positions havingsuch a positional relation that the respective supports clan be seenwhen viewed through each open-face of the cavity, the device can beintegrally molded easily by means of a two-piece mold.

In the above respective embodiments, it is described that the supportsas parts separated from the dielectric core and the cavity are used, orthe supports are molded integrally with the dielectric core and thecavity, as an example. The supports may be molded integrally with thedielectric core and bonded to the inside of the cavity,.or the supportsmay be molded integrally with the cavity, and the dielectric core may bebonded to the supports.

Hereinafter, an example of forming dielectric resonator devices such asvarious filters, synthesizers distributors, and so forth by using pluralresonance modes will be described with reference to FIG. 26.

In FIG. 26, the alternate long and two short dashes line represents acavity. In the cavity, a dielectric core 1 is disposed. A supportingstructure for the dielectric core 1 is omitted. In (A) of this figure,the formation of a band rejection filter is illustrated, as an example.Reference numerals 4 a, 4 b, and 4 c each represent a coupling loop. Thecoupling loop 4 a is coupled to a magnetic field (magnetic field in theTM01 δ−x mode) in a plane parallel to the y-z plane, the coupling loop 4b is coupled to a magnetic field (magnetic field in the TM01 δ−y mode)in a plane parallel to the x-z plane, and the coupling loop 4 c iscoupled to a magnetic field (magnetic field in the TM01 δ−z mode) in aplane parallel to the x-y plane. One end of each of these coupling loops4 a, 4 b and 4 c is grounded. The other ends of the coupling loops 4 aand 4 b, and also, the other ends of the coupling loops 4 b and 4 c areconnected to each other through transmission lines 5, 5 each having anelectrical length which is equal to λ/4 or is odd-number times of λ/4,respectively. The other ends of the coupling loops 4 a, 4 c are used assignal input-output terminals. By this configuration, a band rejectionfilter is obtained in which adjacent resonators of the three resonatorsare connected to a line with a phase difference of π/2.

FIG. 26 (B) shows an example of forming a synthesizer or a distributor.Hereupon, reference numerals 4 a, 4 b, 4 c, and 4 d designate couplingloops. The coupling loop 4 a is coupled to a magnetic field (magneticfield in the TM01 δ−x mode) in a plane parallel to the y-z plane. Thecoupling loop 4 b is coupled to a magnetic field (magnetic field in theTM01 δ−y mode) in a plane parallel) to the x-z plane. The coupling loop4 c is coupled to a magnetic filed (magnetic field in the TM01δ−z mode)in a plane parallel to the x-y plane. Regarding the coupling loop 4 d,the loop plane is inclined to any of the y-z plane, the x-z plane, andthe x-y plane, and coupled to magnetic fields in the above three modes,respectively. One ends of these coupling loops are grounded,respectively, and the other ends are used as signal input or outputterminals. In particular, when the device is used as a synthesizer, asignal is input through the coupling loops 4 a, 4 b, and 4 c, andoutputs from the coupling loop 4 d. When the device is used as adistributor, a signal is input through the coupling loop 4 d, and outputfrom the coupling loops 4 a, 4 b, and 4 c. Accordingly, a synthesizerwith three inputs and one output or a distributor with one input andthree outputs are obtained.

Similarly, a band pass filter can be formed by coupling predeterminedresonance modes through a coupling loop, and a transmission line, ifnecessary.

In the above example, the three resonance modes are utilized. At leastfour modes may be utilized. Further, a composite filter in which a bandpass filter and a band rejection filter are combined can be formed bycoupling some of the plural resonance modes sequentially to form theband pass filter, and making the other resonance modes independent toform the band rejection filter.

Next, an example of a triple mode dielectric resonator device will bedescribed with reference to FIGS. 29 to 33.

FIG. 29 is a perspective view showing the basic constitution portion ofa triplex mode dielectric resonator device. In this figure, referencenumeral 1 designates a square plate-shaped dielectric core of which twosides have substantially the same lengths, and the other one side isshorter than each of the two sides. The reference numerals 2 and 3designate an angular pipe-shaped cavity and a support for supporting adielectric core 1 substantially in the center of the cavity 2,respectively. A conductor film is formed on the outer peripheral surfaceof the cavity 2. Dielectric sheets each having a conductor film formedthereon or metal sheets are disposed on the two open faces to constitutea substantially parallelepiped-shaped shield space. Further, to anopen-face of the cavity 2, an open-end of another cavity is opposed, sothat electromagnetic fields in predetermined resonance modes are coupledto each other to realize a multi-stage.

The supports 3 shown in FIG. 29, made of a ceramic material having alower dielectric constant than the dielectric core 1, are disposedbetween the dielectric core 1 and the inner walls of the cavity 2,respectively, and fired to be integrated. The dielectric core may bedisposed in a metallic case, not using the ceramic cavity as shown inFIG. 29.

FIGS. 30 to 32 show the resonance, modes caused by the dielectric core 1shown in FIG. 29. In these figures, x, y, and z represent theco-ordinate axes in the three dimensional directions shown in FIG. 29.FIGS. 30 to 32 show the cross sectional views of the two-dimensionalplanes, respectively. In FIGS. 30 to 32, a continuous line arrowindicates an electric field vector, a broken line arrow does a magneticfield vector, and symbols “•” and “×” do the directions of an electricfield and a magnetic field, respectively. In FIGS. 30 to 32, shown arethe TE01δ mode (TE01δ−y mode) in the y-direction, the TM01δ mode (TM01δ−x) in the x-direction, and the TM01δ mode (TM01δ−z) in thez-direction.

FIG. 33 shows the relation between the thickness of the dielectric coreand the resonance frequencies in the six modes. In (A), the resonancefrequency is plotted as ordinate. In (B), the resonance frequency ratiobased on the TM01 δ−x mode is plotted as ordinate. In (A) and (B), thethickness of the dielectric core, expressed as oblateness, is plotted asabscissa. The TE01δ−z mode and the TE01δ−x mode are symmetric. A whitetriangle mark representing the TE01δ−z mode, and a black triangle markfor the TE01δ−x mode, overlap. Similarly, the TM01δ−z mode and theTM01δ−x mode are symmetric. Therefore, white circle marks representingthe TE10δ−z mode, and black circle marks for the TM01 δ−x mode overlap.

Like this, as the thickness of the dielectric core is thinned (theoblateness is decreased), the resonance frequencies of the TE01δ−y mode,the TM01δ−x mode, and the TE01δ−z mode have a larger difference fromthose of the TM01δ−y mode, the TE01δ−x, and the TE01δ−z mode,respectively.

In this embodiment, the thickness of the dielectric core is set byutilization of the above described relation, and three modes, namely,the TE01δ−y, TM01δ−x, and TE01δ−z modes are used. The frequencies of theother modes, that is, the TM01 δ−y, TE01δ−x, and TE01δ−z modes are setto be further separated from those of the above-described three modes soas not to be affected by them.

Next, an example of a dielectric filter including the above-describedtriplex mode dielectric resonator device will be described withreference to FIG. 34. In FIG. 34 (A), reference numerals 1 a, 1 ddesignate prism-shaped dielectric cores, and are used as a dielectricresonator in the TM110 mode. Reference numerals 1 b, 1 c designatesquare-sheet shaped dielectric cores in which two sides havesubstantially equal lengths, and the other one side is shorter than eachof the two sides. The dielectric cores are supported at predeterminedpositions in a cavity 2 by means of supports 3, respectively. Thesedielectric cores are used as the above-described triple mode dielectricresonator. The triplex mode consists of three modes, that is, theTM01δ−(x−z) mode, the TE01δ−y mode, and the TM01 δ−(x+z) mode, as shownin (B).

For illustration of the inside of the cavity 2, the thickness of thecavity 2 is omitted, and only the inside thereof is shown by alternatelong and two short dashes lines. Shielding plates are provided at theintermediate positions between adjacent dielectric cores, respectively.

Reference numerals 4 a to 4 e designate coupling loops, respectively, ofwhich the coupling loops 4 b, 4 c, and 4 d are arranged so as to extendover the above shielding plates, respectively. One end of the couplingloop 4 a is connected to the cavity 2, and the other end is connected tothe core conductor of a coaxial connector (not illustrated), forexample. The coupling loop 4 a is disposed in the direction where amagnetic field (line of magnetic force) of the TM 110 mode, caused bythe dielectric core la, passes the loop plane of the coupling loop 4 a,and thereby, the coupling loop 4 a is magnetic field coupled to theTM110 mode generated by the dielectric core 1 a. One end and its nearportion of the coupling loop 4 b are elongated in the direction wherethey are magnetic field coupled to the TM110 mode of the dielectric core1 a. The other end and its near portion are elongated in the directionwhere they are magnetic field coupled to the TM01δ−(x+z) mode of thedielectric core 1 c. The both-ends of the coupling loop 4 b areconnected to the cavity 2. One end and its near portion of the couplingloop 4 c are elongated in the direction where they are magnetic fieldcoupled to the TM01δ−(x+z) mode of the dielectric core 1 b. The otherend is elongated in the direction where it is magnetic field coupled tothe TM01δ−(x−z) mode of the dielectric core 1 b. The both ends of thecoupling loop 4 c are connected to the cavity 2. Further, one end of thecoupling loop 4 d is elongated in the direction where it is magneticfield coupled to the TM01δ−(x+z) mode of the dielectric core 1 c, andthe other end is elongated in the direction that it is magnetic fieldcoupled to the TM110 mode caused by the dielectric core 1 d. The bothends of the coupling loop 4 d are connected to the cavity 2. Thecoupling loop 4 e is arranged in the direction where it is magneticfield coupled to She TM110 mode of the dielectric core 1 d. One end ofthe coupling loop 4 e is connected to the cavity 2, and the other end isconnected to the core conductor of a coaxial connector (notillustrated).

Coupling-conditioning holes h1, h2, h3, and h4 are formed in thedielectric resonator in the triplex mode caused by the dielectric core 1b, and the dielectric resonator in the triple mode caused by thedielectric core 1 c, respectively. For example, by setting thecoupling-conditioning hole h2 to be larger than the hole h3, the balancebetween the electric field strengths at the point A and B shown in FIG.34 (C) is broken, and thereby, energy is transferred from the TM01δ−(x−z) mode to the TE01δ−y mode. By setting the coupling-conditioninghole h4 to be larger than the hole h1, the balance between electricfield strengths at the point C and D shown in (C) is broken, andthereby, energy is transferred from the TE01δ−y mode to the TE01δ−(x+z)mode. Accordingly, the dielectric cores 1 b and 1 c constitute resonatorcircuits in which resonators in three stages are longitudinallyconnected, respectively. Accordingly, the dielectric filter, as a whole,operate as a dielectric filter composed of resonators in eight stages(1+3+3+1) longitudinally connected to each other.

Next, an example of another dielectric filter including theabove-described triplex mode dielectric resonator device will bedescribed with reference to FIG. 35. In the example shown in FIG. 34,the coupling loops, which are coupled to the respective resonance modescaused by adjacent dielectric cores, are provided. However, eachdielectric resonator device may be provided for each dielectric core,independently. In FIG. 35, reference numerals 6 a, 6 b, 6 c, and 6 ddesignate dielectric resonator devices, respectively. These correspondto the resonators which are caused by the respective dielectric coresshown in FIG. 34 and are separated from each other. The dielectricresonator devices are arranged at positions as distant as possible sothat two coupling loops provided for the respective dielectric resonatordevices don't interfere with each other. Reference numerals 4 a, 4 b 1,4 b 2, 4 c 1, 4 c 2, 4 d 1, 4 d 2, and 4 e designate respective couplingloops. One end of each of the coupling loops is grounded inside of thecavity, and the other end is connected to the core conductor of acoaxial cable by soldering or caulking. The outer conductor of thecoaxial cable is connected to the cavity by soldering or the like.Regarding the dielectric resonator 6 d, the figure showing the couplingloop 4 d 2 and the figure showing the coupling loop 4 e are separatelyprovided for simple illustration.

The coupling loops 4 a, 4 b 1 are coupled to the dielectric core 1 a,respectively. The coupling loop 4 b 2 is coupled to the TM01δ−(x−z) ofthe dielectric core 1 b. The coupling loop 4 c 1 is coupled to the TM01δ−(x+z) of the dielectric core 1 b. Similarly, the coupling loop 4 c 2is coupled to the TM01δ−(x−z) of the dielectric core 1 c. The couplingloop 4 d 1 is coupled to the TM01δ−(x+z) of the dielectric core 1 c. Thecoupling loop's 4 d 2 and 4 e are coupled to the dielectric core 1 d,respectively.

Accordingly, the coupling loops 4 b 1 and 4 b 2 are connected through acoaxial cable, the coupling loops 4 c 1 and 4 c 2 are connected througha coaxial cable, and further the coupling loops 4 d 1 and 4 d 2 areconnected through a coaxial cable, and thereby, the whole of thedielectric resonator devices operates as a dielectric filter comprisingthe resonators in eight stages (1+3+3+1) longitudinally connected toeach other, similarly to that shown in FIG. 34.

Next, an example of the configuration of a transmission-receptionshearing device will be shown in FIG. 36. Hereupon, a transmissionfilter and a reception filter are band-pass filters each comprising theabove dielectric filter. The transmission filter passes the frequency ofa transmission signal, and the reception filter passes the frequency ofa reception signal. The connection position between the output port ofthe transmission filter and the input port of the reception filter issuch that it presents the relation that the electrical length betweenthe connection point and the equivalent short-circuit plane of theresonator in the final stage of the transmission filter is odd-numbertimes of the ¼ wave length at a reception signal frequency, and theelectrical length between the above-described connection point and theequivalent short-circuit plane of the resonator in the first stage ofthe reception filter of the reception filter is odd-number times of the¼ wavelength at a transmission signal frequency. Thereby, thetransmission signal and the reception signal can be securely branched.

As seen in the above-description, similarly, by disposing pluraldielectric filters between the port for use in common and the individualports, a diplexer or a multiplexer can be formed.

FIG. 37 is a block diagram showing the configuration of a communicationdevice including the above-described transmission-reception shearingdevice (duplexer). The high frequency section of the communicationdevice is formed by connecting a transmission circuit to the input portof a transmission filter, connecting a reception circuit to the outputport of a reception filter, and connecting an antenna to theinput-output port of the duplexer.

Further, a communication device small in size, having a high efficiencycan be obtained as follows. Circuit component such as the diplexer, themultiplexer, the synthesizer, the distributor each described above, andthe like are formed of the multimode dielectric resonator devices, and acommunication device are formed of these circuit components.

As seen in the above-description; according to the present inventiondefined in claim 1, the supporting structure for the dielectric core issimplified. Further, since the dielectric core having a substantialparallelepiped-shape, operative to resonate in plural modes is used,plural resonators can be formed without plural dielectric cores beingarranged, and a dielectric resonator device having stablecharacteristics can be formed.

According to the invention defined in claim 2, the concentration of anelectromagnetic field energy onto a dielectric core is enhanced, thedielectric loss is reduced, and the Q₀ can be maintained at a highvalue.

According to the present invention defined in claim 3, supports asindividually-separate parts become unnecessary. The positional accuracyof the supporting portions for the cavity and the dielectric core, andmoreover, the positioning accuracy of the dielectric core into thecavity are enhanced. Thus, a multimode dielectric resonator device whichis inexpensive and has stable characteristics can be obtained.

According to the invention defined in one of claims 4 and 5, themechanical strength of a supporting portion per overall cross sectionalarea can be enhanced. Further, in the TM modes, the reduction of Q₀ inthe mode in which the supporting portions or supports are elongatedperpendicularly to the rotation plane of a magnetic field can beinhibited.

According to the present invention defined in claim 6, the reduction ofQ₀ in a mode excluding the TM modes in which the supporting portions orsupports are elongated perpendicularly to the rotation plane of amagnetic field can be inhibited.

According to the present invention defined in claim 7, by setting thedrafting direction of a mold to be coincident with the axial directionof the angular pipe-shape, the cavity and the dielectric core can bemolded integrally, easily by means of the mold having a simplestructure.

According to the present invention defined in claim 8, a dielectricfilter having a filter characteristic with a high Q and small in sizecan be obtained.

According to the present invention defined in claim 9, a compositedielectric filter small in size, having a low loss can be obtained.

According to the present invention defined in claim 10, a synthesizersmall in size, having a low loss can be obtained.

According to the present invention defined in claim 6, the reduction ofQ₀ in a mode excluding the TM modes in which the supporting portions orsupports are elongated perpendicularly to the rotation plane of amagnetic field can be inhibited.

According to the present invention defined in claim 7, by setting thedrafting direction of a mold to be coincident with the axial directionof the angular pipe-shape, the cavity and the dielectric core can bemolded integrally, easily by means of the mold having a simplestructure.

According to the present invention defined in claim 8, a dielectricfilter having a filter characteristic with a high Q and small in sizecan be obtained.

According to the present invention defined in claim 9, a compositedielectric filter small in size, having a low loss can be obtained.

According to the present invention defined in claim 10, a synthesizersmall in size, having a low loss can be obtained.

According to the present invention defined in claim 11, a distributorsmall in size, having a low loss can be obtained.

According to the present invention defined in claim 12 a communicationdevice small in size, having a low loss can be obtained.

Industrial Applicability

As seen in the above-description, the multimode dielectric resonatordevice, the dielectric filter, the composite dielectric filter, thedistributor, and the communication device including the same accordingto the present invention can be used in a wide variety of electronicapparatuses, for example, base stations in mobile communication.

What is claimed is:
 1. A multimode dielectric resonator devicecomprising a dielectric core having a substantial parallelepiped-shaped,operative to resonate in plural modes, and supported substantially inthe center of a cavity having a substantial parallelepiped-shape in thestate that the dielectric core is separated from the inner walls of thecavity at predetermined intervals, respectively; characterized in thatthe dielectric core is supported with respect to the respective innerwalls of the cavity by a support having a lower dielectric constant thanthe dielectric core, wherein both the dielectric core and the supportare made of a ceramic material.
 2. A multimode dielectric resonatordevice according to claim 1, characterized in that the dielectric coreis supported with respect to the respective inner walls of the cavity bya supporting portion molded integrally with the dielectric core or thecavity.
 3. A multimode dielectric resonator device according to any oneof claims 1 and 2, characterized in that the support or a supportingportion is provided in a ridge portion of the dielectric core or aportion along a ridge line of the dielectric core.
 4. A multimodedielectric resonator device according to any one of claims 1 and 2,characterized in that the support or supporting portion is provided nearto an apex of the dielectric core.
 5. A multimode dielectric resonatordevice according to any one of claims 1 and 2, characterized in that thesupport or supporting portion is provided in the center of one face ofthe dielectric core.
 6. A multimode dielectric resonator deviceaccording to claim 1, characterized in that a part of or the whole ofthe cavity comprises a molded product having an angular pipe-shape, andthe dielectric core is supported with respect to the inner walls of themolded product by the support or supporting portion.
 7. A dielectricfilter comprising the multimode dielectric resonator device according toclaim 1, and externally coupling means for externally coupling to apredetermined mode of the multimode dielectric resonator device.
 8. Acomposite dielectric filter comprising the dielectric filter accordingto claims 7 provided between a single or plural ports to be used incommon and plural ports to be used individually.
 9. A synthesizercomprising the multimode dielectric resonator device according to claim1, independently, externally coupling means for externally coupling toplural predetermined modes of the multimode dielectric resonator device,respectively, independently, and commonly externally coupling means forexternally coupling to plural predetermined modes of the multimodedielectric resonator device in common, wherein the commonly externallycoupling means is an output port, and the plural independentlyexternally coupling means are input ports.
 10. A distributor comprisingthe multimode dielectric resonator device according to claim 1,independently, externally coupling means for externally coupling toplural predetermined modes of the multimode dielectric resonator device,independently, and commonly externally coupling means for externallycoupling to plural predetermined modes of the multimode dielectricresonator device in common, wherein the commonly externally couplingmeans is an input port, and the plural independently externally couplingmeans are output ports.
 11. A communicating device comprising; ahigh-frequency circuit selected from the group consisting of atransmission circuit and reception circuit; and connected to saidhigh-frequency circuit, the composite dielectric filter according toclaim
 8. 12. A synthesizer comprising the multimode dielectric resonatordevice according to claim 1, a plurality of input ports whichindependently provide external coupling to respective predeterminedmodes of the multimode dielectric resonator device, and a common outputport which provides external coupling to plural predetermined modes ofthe multimode dielectric resonator device.
 13. A distributor comprisingthe multimode dielectric resonator device according to claim 1, a commoninput port which provides external coupling to plural predeterminedmodes of the multimode dielectric resonator device, and a plurality ofoutput ports which independently provide external coupling to respectivepredetermined modes of the multimode dielectric resonator device.
 14. Acommunication device comprising: the synthesizer according to claim 9 orclaim 12; a first high-frequency circuit connected to one of said inputports; and a second high-frequency circuit connected to another one ofsaid input ports.
 15. A communication device comprising: the distributoraccording to claim 10 or claim 13; a first high-frequency circuitconnected to one of said output ports; and a second high-frequencycircuit connected to another one of said output ports.